1) Field of the Invention
This invention relates to an image forming apparatus, and a sheet arranging method for the apparatus, and more particularly to an image forming apparatus which forms images of two pages on a single cut sheet.
2) Description of the Related Art
An image forming apparatus is available which is able to form images of a plurality of pages on one cut sheet. In the image forming apparatus, the cut sheet, after being printed, is handled as follows: The operator takes the cut sheet out of the apparatus, and loads it in a sheet post-processing apparatus positioned far from the image forming apparatus, where it is subjected to a sheet cutting operation; that is, it is cut into smaller sheets the number of which corresponds to the pages bearing the images, and to a sheet arranging operation; that is, those smaller sheets are arranged in order. Alternatively, the cut sheet taken out of the image forming apparatus is delivered to a sheet post-processing apparatus set adjacent to the image forming apparatus, where, similarly as in the above-described case, it is cut into smaller sheets, and the smaller sheets are arranged in order.
In the former system, the cut sheet taken out of the image forming apparatus must be loaded in the sheet post-processing apparatus located far from the image forming apparatus. This sheet loading operation is rather troublesome.
This difficulty may be eliminated by modifying the latter system as follows: The image forming apparatus and the sheet arranging apparatus are electrically or mechanically coupled to each other so that the cut sheet is automatically transferred from the image forming apparatus to the sheet arranging apparatus. In the system thus modified, the sheet can be handled efficiently. If the sheets are jammed in the sheet post-processing apparatus, the following process can be immediately suspended by applying a sheet jamming signal to the image forming apparatus. That is, it is possible to allow the image forming apparatus and the sheet post-processing apparatus to cooperate with each other to some extent.
However, the system is disadvantageous, for instance, in the following points:
After removal of the jammed sheets, it cannot be determined from where the printing operation should be started. In general, even standard sheets have a dimensional tolerance of about 2 mm, and it is impossible to accurately cut a standard sheet into smaller sheets with the dimensional tolerance taken into account. In addition, operating data are limited which can be transmitted between the image forming apparatus and the sheet post-processing apparatus. Moreover, equipment required for the image forming operation and the sheet cutting operation is physically very large in scale.